Every night for his feeding between 7-9pm, my 7 week old will fuss. He will latch for a few minutes and then all of a sudden he'll unlatch and cry and then try to latch again frantically- this will continue for the whole feeding until he tires himself out. This doesn't happen because of a strong let-down (he does it throughout the feeding, not just at a let-down). He doesn't do this any other time of the day- and he only started this last week- he had been nursing fine before that. I had some complications, so we've had to supplement with formula occasionally and when we give him a bottle for this evening feeding he does the same thing (not as severely but still fights it). I know he's hungry because as soon as we take him off, he's frantically rooting. We burp him often, but he does seem to toot a lot at this time of night. We've tried gas drops and gripe water but haven't seen an improvement with either. Any suggestions?